Fire extinguisher composition



No Drawing.

Patented May 23, 1933 V f STATES A'TENT orrlca CHARLES A. THOMAS AND CARROLL A. HOCHWALT, 0F DAYTON, OHIO, ASSIGNOBS TO THE EYE-mm COMPANY, OF DAYTON, OHIO, .AOOIQPOBAIION OHIO EXTINGUISHEB COMPOSITION This-invention relates to fire extinguishers, and more particularly to charges for such extinguishers.

One of the principal objects of the invention is to provide a fire extinguisher charge which has superior fireextinguishing prop-.

. disclosure and claims.

Portablefi re extinguishers, as heretofore manufactured for many years, have been generally of two types,-one type having some form of pumping mechanlsm for ex pelling the fire extinguishing liquid, and the other type having some form of chemical charge of such characteristics that during vuse chemical reaction will take place to produce a gaseous pressure for expelling the fire extinguishing liquid. 1 Of the latter class of extinguishers, that generally known as the soda and acid extinguisher is typical. Such an extinguisher as heretofore generally manufactured has consisted of a casing containing a fire extinguishing liquid, ordinarily a sol tion of sodium bicarbonate in water, a bottle of some acid, such as sulfuric acid, being mounted within the casing so that when the extinguisher is inverted for use the acid will escape into the solution and react therewith to generate carbon dioxide which in turn exerts a pressure upon the-extinguishing solution to expel it from the extinguisher. The expelled liquid from such an extinguisher consists primarily of the reaction product of the sodium bicarbonate and the acid, this liquid carrying some carbon dioxide bubbles.

One principal objection to an extinguisher of this .character with the sodium bicarbonate charges heretofore used, is that the sodium bicarbonate solution will not withstand very low temperatures.

Another objection is that the chemicals Application filed August 8, 1927. Serial No. 211,251.

employed in the ordinary soda-acid extinguisher will not react efliciently at such low temperatures, and for practical fire extinguisher operation become practically inert at temperatures considerably above-40 0., satisfactory functioning at which temperature The Underwriters Laboratories prescribe as prerequisite' to the certifying of such extinguisher as being of a preferred character. a

'We have discovered that a water solution of potassium carbonate repared in accordance with this'invention has exceptional and unexpected fire extinguishing properties,

which render it a super or fire extinguishing medium to be discharged directly upon a fire... It is quite superior in its extinguishing effect to the reaction product heretofore discharged from the usual soda-acid t peof extinguisheras the extinguishing flui Potassium' carbonate solution is more effective in the extinguishing of wood fires than carbon tetrachloride, and in addition does not produce objectionable fumes or odors when expelled upon fires. It is, also, as effective as carbon tetrachloride in extinguishing oil fires-in open vessels. None of the other aqueous carbonate solutions commonly used in extinguishers of the chemical reaction type areefi'ective for oil fires. We have found that relatively high concentrations of the potassium carbonate dis solved in water give the best results. Exr cellent results have been secured by using solutions containing 34% or more by weight of potassium carbonate. While weaker solutions have effective fire extinguishing properties, we prefer to use solutions of higher concentrations, as giving the best results. For example, in actual usage the potassium carbonate solution prepared in accordance,

. lution of potassium 4 cially, for fire extinguisher use.

.-ica1ly inert with containing 39.6% by weight of potassium carbonate, this solution freezing at -36.5

We have found however that a water socarbonate can be producedwhich will remain liquid below "40 (3. Solutions of the relatively hi h concentrations we prefer to use will un er certain operating conditions remain li aid at temperatures below -40 C. rovi ed the concentration of the solution oes not approach too closely the saturation point at 0 As the concentration of a water solution of potassium carbonate increases, the freezing point falls until a concentration of 39.6% weight is reached, and thereafter rises as e concentration is further increased. By using a solution having a concentration not above 42% by weight of potassium carbonate, thesolution will remain liquid at the desired low temperatures which are below its normally expected freezing point.

A solution prepared from an anhydrous potassium carbonate salt, or one which has been freshly calcined, will more readily withstand these excessively low temperatures than a solution prepared from a crystalline salt of potassium carbonate containing water of crystallization, or otassium carbonate which has been'allowed to stand exposed to the air and to absorb moisture. y

The freezing point of a-carbonatesolution may be lowered by mixing therewith certain freezing temperature depressants. *But heretofore there has been no such depressant which was free from serious objections. espe- Such freezing temperaturedepressant should be chemrespect to the solution. Further, it is desirable that only smalLproportions of such depressant be used, so that the solution may contain per unit volume the desired large quantities of potassium carhigh solubility of.

bonate. The .extremely potassium carbonate enables large quantities to be dissolved within relatively small vol ,umes of water; and from the standpoint of economy as well as to maintain the highly efiective extinguishing properties of the potassium carbonate solution. preferably only small amounts of other substances. such as the depressant, are incorporated therewith.

One freezing temperature depressant which satisfies the above-mentioned requirements is ethylene glycol. which is structurally a polyhydric alcohoL- Ethylene glycol need be used in only small proportions. satisfactory results being-obtained with as low as (ingredients. be used to secure the desired anti-corrosive anoe with this invention,

have freezin narrates freezing solution at such extremely low temperatures, from the standpoint of economy and to avoid reducing the concentration of the otassium carbonate below the desired high y effective range, only such small proportions as mentioned are used. Another suitable freezing temperature depressant is glycerine, also a polyhydric alcohol, this be ing used in substantiall the same proportions as ethylene glyco A leevulose containing material, such as ordinary bees honey, is also a suitable freezing temperature depressant for the potassium carbonate solution, about 2% to 5% byweight of honey giving satisfactory results.

A potassium carbonate solution tends to produce objectionable corrosion of the extinguisher fluid container. We have found that this corrosion may be prevented by incorporating therewith a compound liberating chromate ions in the solution. Any suitable chromate may be used, butpreferably a soluble chromate such as an alkali metal chromate, which may be readily put into solution, is selected. Dichromates may also be used for this purpose. Wli'en dichromates are added to the solution they are converted into chromates with the production of the chromate ions in the solution. Th6 chromates, when added originally or 95 when formed from dichromates in solution, are chemically inert with respect to the solution, and so may be used as a part of the extinguisher charge. We preferably select sodium dichromate as the\ anti-corrosive agent because of its solubility characteristics and cheapness. This compound not only functions to prevent corrosion within the extinguisher, but also serves as a freezing temrature depressant in the solution, assisting 1n the lowering of the freezing point. Only small amounts of the anti-corrosive agent need-be used, as little as .8% by weight of sodium dichromate being satisfactory. We prefer to use from .8% to 2% by weight of sodium dichromatein the solution depending upon the concentrations of the other Higher percentages need not and freezing temperature depressant properties.

As examples of otassium carbonate fire extinguishing solutions prepared inaccordwhich solutions have superior fire extinguishing properties, have 'no objectionable corrosive eflect, and points below -40 0., the following',are isted for illustrative purposesi Pement.

.8% by weight in a solution containing the proper concentration of potassium. carbonsize. We prefer to use from .8% to 5% by weight of ethylene glycol, depending upon f f -the -proportionsof the other ingredients of the solution.

* bywetght p (1) e9.e K 00a 58. 8 5,0

. 8-..... Ethylene glycol 8.... Nagcrgor While higher percentages of v 100.0,-" Freezing points-41 C.

" ethylene glycol may be used to give a now 1 siu'm carbonate Percent 3 ww m (2) 39. 6--" K2008 iii? 1 l 1 5. 0. t y ene gyco .8 Na Cr fl x 1001)---- Freezing point 46 C.'

Percent I bywelgltt (3) 39. 6--" K COS 5. 0 t y ene g ycol 2- 0 Nfl CI' O- I I 100.0"; Freezing point 49 C.

It is to be noted from reference to Examples (1) and (2) that increasing the percentages of ethylene glycol while maintaining the percentages of potassium carbonate and sodium dichromate constant lowersthe freezing point within the range given. At-

tention is also called to Examples (2) and (3) which illustratejpart-icular y the freezdiumdichromate, the percentages of potasand ethylene glycol being maintained constant in these examples. In general, as the percentage of potassium carbonate is varied below or above 39.6%, increasing percentages of ethylene glycol should be added to give the desired low freezing point. Thus, while .8% ethylene glycol is sufiiicient when using 39.6% by weight of potassium carbonata-this percentage should be increased somewhat as the proportion of potassium carbonate is reduced and approaches 34% .or is increased and approaches 42%. However, percentages,

of 2% to 5% of ethylene glycol may be used throughout the range mentioned with satis-" factory results use.

for practical fire extinguisher be readily mixed in the proper proportions k and shipped in the solid state. Moreover,

col may be mixed with the small amount of the liquid ethylene glythe solid salt or salt mixture, and the solid phase of the carbonate material maintained, the ethylene glycol being readily held within the salt. The result ant mixture retains in all respects its solid characteristics, and can be readily handled. Thus a charge mixed in the proper proportions may be shipped in the solid state to the user, where. it is placed in solution in the proper amount of water, ing usually marked to indicate the proper water level.

The charge is quite readily ing on the surface of over. Any

the extinguisher besoluble, so the solution of the dry charge by the user is easily effected.

When the guishin liquid is exposed to the atmosphere, particu arly when exposed to a damp or humid atmosphere, the solution tends to absorb moisture and thereby changeits concentration, which affects its freezing point. We have found that this may be prevented by using, within the extinguisher, .a non-miscible liquid of lower specific gravity than the carbonate solution, this liquid remainthe potassium carbonate solution to form a sealing layer theresuitable sealing liquid having thepotassium carbonate fire extinabove mentioned properties, and which is inert with respect to the solution, may be usedx Very satisfactory results are secured when a parafline oil is used as the sealing 1i uid. Only a sufficient amount of the para e oil or other sealing liquid need be used to cover the exposed surface of the carbonate solution with a thin sealing layer. I The fire extinguishing liquid or solution is adapted to be used in a chemical type extinguisher, orin any other type of extinguisher, pump tank, or the like having means for expelling the liquid itself upon the fire. Thus the'potassium carbonate solution may be pumped directly upon the. fire from a pump extinguisher. or the potassium carbonate solution may' be used as the extinguishing liquid in a chemical type extin uisher having a separate gas generating c arge for expellin this liquid; or the potassiu'n'r carbonate so ution itself may be used as a part of the gas generating portion of the charge. We prefer to use as the acid constituent of the charge a compound containing a sulfonic acid radical, such. as a halogenated sulfonic acid, for the reason that such a compound will react with high eficiency with a carbonate. solution even at such extrem ly low temperatures. Such a halogenated sulfonic acid is chlorosulfomc acid or in fact any sulfonic acid containing any element of the halogen group. When chlorosulfonic isused, means is preferably provided for preventing objectionable fummg of the acid. However, when conditions of use warrant other commonly used acids, such as sulfuric and hydrochloric acid, may be used as the acid portion of the charge. When used in such a chemical reaction extinguisher, this potassium carbonate charge its its

is particularly advantageous since in such a solution there is present a very large excess of carbonate over that required for reaction with the acid used. The carbonate solution is provided to perform a double function,namely, a small portion of the solution reacts with the acid to generate an expelling gas, and the balance of the solution is expelled directly from the container as such without reaction and serves as a ing medium, said carbonate solution contain ing a considerable excess of carbonate of potassium over the chemical equivalent amount which reacts with said acid, a ma'or portion 5 of the carbonate of potassium in t e solution being expelled as suchfrom the extinguisher, the expelled liquid thereby having high fire extin uishing properties. v v

7. charge for fire extinguishers consisting of two normally separated gas enerating portions, comprising an acid, an a solution containing approximately 34% to 42% by weight of a carbonate of potassium having high fire extinguishing properties adapted to react with said acid to generate an expelling gas for expelling the said solution rom the extinguisher as the fire extinguishing medium, said carbonate of potassium solution being of such concentration and supplied in such-volume that less than 10% of the carbonate of potassium in said solution is used in the reaction with said acid, the balance of said carbonate of potassium in the solution being expelled 'as such from 1 the extinguisher, the expelled liquid consisting primarily of the solution of the carbonate of potassium having high fire extirigui'shin properties.

8. A fire extinguishing liquid having hi h fire extinguishing roperties' adapted to e projected upon a re, comprising a water solution containing approximately 34% t0 42% by weight of a car onate of potassium, and less than 3% by weight of a chromate 35 compound.

Y '9. A fire extinguishing liquid having hi h fire extinguishing properties adapted to e projected upon a fire, comprising as essential ingredients a water solution of potassium carbonate containing approximately 34% to 42% by weight of potassium carbonate, and a temperature depressant in the amount of not more than 10% by weight.

10. A fire extinguishing liquid having 45 high fire extinguishing properties adapted to be projected upon a fire, comprising as essential ingredients a water solution of po- 'tassium carbonate containing approximately 34 to 42% by weight of potassium carbonate,

and a temperature depressant, said solution with temperature depressant having a freezing point at least as low as 40 C.

In testimony whereof we hereto aflix our signatures. CHARLES A. THOMAS.

CARROLL A. HOCHWALT. 

